1. Field of the Invention
The present invention generally relates to engines used with saddle-type vehicles.
2. Description of the Related Art
Saddle-type vehicles can have a number of different configurations, such as motorcycles, scooters, four-wheeled vehicles and the like. The engines of such saddle-type vehicles often include integrated auxiliary components, such as a continuously variable transmission and a speed reduction mechanism. Together with these auxiliary components, the engines are mounted to the body or frame of the vehicle.
JP-A-2001-3723 (hereinafter, referred to as Patent Document 1) discloses an engine including a V-belt continuously variable transmission, a centrifugal clutch, and a speed-reduction mechanism. In this engine, a driving pulley (hereinafter, referred to as a primary sheave) of the V-belt transmission is mounted to the crankshaft of the engine. A driven pulley (hereinafter, referred to as a secondary sheave) of the V-belt transmission connects to a drive shaft through a centrifugal clutch and an idle shaft of the speed-reduction mechanism. Of course, the engine includes various rotating shafts therein. The shafts are arranged in a transverse orientation such that the arrangement of the shafts can best be described by a side view of the engine. In the engine disclosed in Patent Document 1, as shown in FIG. 5, a secondary sheave shaft that carries the secondary sheave is arranged vertically lower than a drive shaft.
As shown in FIG. 6 of JP-A-2001-65650 (hereinafter, referred to as Patent Document 2), Patent Document 2 discloses an engine having a secondary sheave shaft arranged vertically higher than a drive shaft associated with the engine. The engine has a speed-reduction mechanism between the secondary sheave shaft and the drive shaft.
As shown in FIG. 2 of JP-A-2002-19682 (hereinafter, referred to as Patent Document 3), Patent Document 3 discloses an engine having a secondary sheave shaft and a drive shaft that are generally at the same vertical height. In other words, the secondary sheave shaft and the drive shaft of the engine are arranged substantially on the same vertical level. Also the engine includes a speed-reduction mechanism that is positioned between the secondary sheave shaft and the drive shaft.